Lesson plan
Formazine
Formazine (formazin) is a heterocyclic polymer produced by reaction of hexamethylenetetramine with hydrazine sulfate. The hexamethylenetetramine tetrahedral cage-like structure, similar to adamantane, serves as molecular building block to form a tridimensional polymeric network. Formazine is very poorly soluble in water and when directly synthesized in aqueous solution, by simply mixing its two highly soluble precursors, it forms small size colloidal particles. These organic colloids are responsible of the light scattering of the formazine suspensions in all the directions. Optical properties of colloidal suspensions depend on the suspended particles size and size distribution. Because formazine is a stable synthetic material with uniform particle size it is commonly used as a standard to calibrate turbidimeters and to control the reproducibility of their measurements. Formazin use was first proposed by Kingsbury et al. (1926) for the rapid standardization of turbidity measurements of albumin in urine. The unit is called Formazin Turbidity Unit (FTU). A suspension of 1.25 mg/L hydrazine sulfate and 12.5 mg/L hexamethylenetetramine in water has a turbidity of one FTU. In the United States environmental monitoring the turbidity standard unit is called Nephelometric Turbidity Units (NTU), while the international standard unit is called Formazin Nephelometric Unit (FNU).…
Article summary
Formazine (formazin) is a heterocyclic polymer produced by reaction of hexamethylenetetramine with hydrazine sulfate. The hexamethylenetetramine tetrahedral cage-like structure, similar to adamantane, serves as molecular building block to form a tridimensional polymeric network. Formazine is very poorly soluble in water and when directly synthesized in aqueous solution, by simply mixing its two highly soluble precursors, it forms small size colloidal particles. These organic colloids are responsible of the light scattering of the formazine suspensions in all the directions. Optical properties of colloidal suspensions depend on the suspended particles size and size distribution. Because formazine is a stable synthetic material with uniform particle size it is commonly used as a standard to calibrate turbidimeters and to control the reproducibility of their measurements. Formazin use was first proposed by Kingsbury et al. (1926) for the rapid standardization of turbidity measurements of albumin in urine. The unit is called Formazin Turbidity Unit (FTU). A suspension of 1.25 mg/L hydrazine sulfate and 12.5 mg/L hexamethylenetetramine in water has a turbidity of one FTU. In the United States environmental monitoring the turbidity standard unit is called Nephelometric Turbidity Units (NTU), while the international standard unit is called Formazin Nephelometric Unit (FNU).…
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.